Constant air volume device in air conditioning

ABSTRACT

A constant air volume device for air conditioning wherein the air volume can be kept constant regardless of the change in the air pressure and further the constant air volume can be adjusted.

United States Patent Inventor ToshiyukiMurakami [56] ReferencesCitedYokohama-SH, J p UNITED STATES PATENTS g 2 3 653,743 7/1900 Jewell .2137/504x Patented Fem-23,1197! 2,022,143 11/1935 Mottershall 137/504x2,584,418 2/1952 Branson 137/504 Ass'gnee Cent" 3,122,162 2/1964 Sands137/504x Japan FOREIGN PATENTS 721,031 12/1954 Great Britain 137/504CONSTANT AIR VOLUME DEVICE IN AIR 5 PrimaryExaminer-Henry T. KlinksiekAttorney- McGlew and Toren CONDITIONING v 2 claims 8 Drawing FigsABSTRACT: A constant air volume device for air condition- U.S. 137/504ing wherein the air volume can be kept constant regardless of Int. (IFl6k 31/12 the change in the air pressure and further the constant airField of Search volume can be adjusted,

PATENTEDFEBNIQYI 3565105 sum 1 OF 2 INVENTOR. Tosmyuill MuflnKnm MMMMPATENTEDFtsz 3 |97l SHEET 2 or 2 FIG.6.

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+ Ywg Mann/mm WMMM CONSTANT AIR VOLUME DEVICE IN AIR CONDITIONING BRIEFEXPLANATION OF DRAWINGS The drawings show an example of the presentinvention, wherein FIG. 1 is a cross-sectional view of the centerportion of a device in accordance with the present invention; FIG. 2 isthe same cross-sectional view when air pressure is being received; FIG.3 is an air pressure-speed diagram; FIG. 4 is a diagram for the loadonto a conical spring and its deflection; FIGS. 5 and 6 are horizontalcross-sectional view and vertical cross-sectional view, respectively,showing the structure of the device; and FIGS. 7 and 8 are verticalsectional view and horizontal sectional view, respectively, showing anexample for the application of the device.

DETAILED EXPLANATION OF THE PRESENT INVENTION The present inventionrelates to a constant air volume device in air conditioning. In acontrol system of an ordinary type or of a damper type, the air volumeexhausted out of each outlet varies depending on the changes in thepressure in the source of air, and also depending on the change in thepressure within ducts, and air is sent to a number of rooms throughducts diverging out of the source of air. When the air volume in any oneof such rooms is adjusted, the air volume exhausted out of other roomschanges, therefore, it has been difficult to send air in the amountoriginally planned and designed to each room.

In view of the above, it is planned that a predetermined amount of airis constantly sent to each outlet through an automatic control even whenthe air pressure changes at the source of air and/or in the air supplyduct, and moreover when the air volume needs to be changed later, it canbe adjusted independently and freely. And at the same time the structureof the device can be quiet simple and the device can be made at with avery low cost.

In conventional constant air volume devices, the constant air volume isset beforehand at a factory or even when it can be adjusted at the placewhere it is installed, the constant air volume can be adjusted at theplace where it is installed, the constant air volume can be adjustedonly within a small range. Contrary to this, in the device disclosedherein, the constant air volume can be adjusted with an almost entirerange and further be a very simple method.

Next, the mechanism of the device shall be explained in reference to thedrawings.

In FIG. 1 and FIG. 2, a conical spring is shown by 1, and 2 is an airpressure plate attached to its wider diameter end 1', wherein an axle 4is inserted through an axle hole 3, which is bored at the center of theair pressure plate 2, and through a narrower diameter end 1" of theconical spring 1. And 5 is a supporting bar provided in a casing 6, andan end of said axle 4 protruding out of the smaller diameter end 1" ofthe conical spring is fixed to the center of said supporting bar with anut 7. In the drawings an arrow F shows the direction of the air blowingin.

The conical spring 1 will have such deflection L with a parabolic curvea shown in FIG. 4 against the load R working on the air pressure plate2. And at the same time, a cross-sectional area A of the air passagewithin the casing (when the air tained by the following formula:

An since Vis in proportion to /A P as shown in FIG. 3

A C X A xvii P, wherein V represents the speed of flow of air and Cshows a coefficient (C has an almost constant value).

Therefore, the condition for always maintaining Q in a constant valueregardless of change in the value of P, will be having A change inproportion to V 7 Thus, it is necessary to have I change in proportionto This can be quite easily done by using the conical spring mentionedabove.

Thus, it can be made possible to always discharge air in a constantvolume out of an outlet by an automatic control even when the airpressure P within the source of air and/or the air supply duct changes.

In a central duct system with one source of air, the device can beinstalled at an appropriate position in the duct or near the outlet, orwithin a sterilizing box having blowout outlets, regardless of the airpassage lay out, and it can be directly connected to an air conditioner.At the same time, when air flows towards the outlet along the externalsurface of the conical spring which is pressed down as air pressure isgiven, the resistance is small and the volume of sound by flow of air isalso small.

Furthermore the device has such advantages that the structure andmanufacture of the same will be very simple compared to conventionaldevices, and can be obtained with a very low cost, through the use ofthe conical spiing.

The conical spring in the present invention is not limited to suchspring as being wound in a conical shape, but it can be of such typethat the diameter is gradually reduced from the wider diameter endtowards the narrower diameter end and it does not have to have a certaincross-sectional shape.

Now a concrete explanation will be given based on an example shown onthe drawings.

Example The control device for constant air volume which is adjustableas shown in FIG. 5 and FIG. 6 consists of an outer casing 10, innercasing 11, a conical spring 12 and an air pressure plate 13 as its maincomponents. Each of the inner casing 11 and outer casing 10 has slits 14arranged in a circumferential direction with uniform intervals, and thearea of the opening varies depending on the position where the bothcasings overlap. The 0 shown in FIG. 5 represents the degree of openingof the slit 14.

The inner casing 11 is fixed to a frame 15. An the degree of opening ofthe slits 14 is adjusted by rotating the outer casing 10 with an openingdegree control handle 17 attached to one end of a central axle 16 whichextends through the inner casing and at its other end is fixed to theouter casing 10 located around the inner casing 1 1.

Therefore the air is, as shown in FIG. 6, first blown against the airpressure plate 13, then is diverged to the circumference and is sentinto the inner casing 11 through the slit openings 14 of the inner andouter casings, then is discharged to outside.

In this case the spring 12 of the air pressure plate 13 expands andcontracts mainly due to the difference in the air pressure between theupstream and the down stream air flow, and the rate of such expansionand contraction is arranged so that it corresponds to the relationshipbetween the air pressure difference and the speed of the upstream airpassing through of overlapping of the slits 14 in the inner and outercasings. Therefore, the constant volume of air can be adjustedbychanging the width of the slit opening with the rotation of thecentral axle 16.

Such an adjustment can be done by remote control, and when a calibrationis made having a degree of rotation of the axle and a volume of aircorresponding to each other, the volume of air which needs to be keptconstant can be precisely established by the air volume calibration. Asupporting bar 18 is used to secure the lower end of the axle 16.

FIG. 7 and FIG. 8 show an application example of the above mentionedcontrol devices for constant air volume which is adjustable. Thesedrawings shown a case where three of such adjustable control devices forconstant air volume as shown in FIG. and FIG. 6 are installed in a duct20.

Iclaim:

l. A constant air volume device for use in air-conditioning apparatusand the like comprising a tubular wall section forming the upstreamportion of an axially extending air flow passageway having an inlet atone end thereof, wall means secured to said tubular wall section spacedaxially from the inlet end thereof and forming a downstream continuationof the air flow passageway having a smaller cross-sectional area thanand in alignment with the portion of said air flow passageway formed bysaid tubular section, a support bar attached to and extendingtransversely across said wall means forming the downstream continuationof the air flow passageway at a location spaced axially downstream fromthe upstream and of said wall means, a shaft member extending axiallythrough the air flow passageway from said tubular wall section into saidwall means and secured at its downstream and to said support bar, aconically shaped spring member disposed within and extending in thedirection of air flow within the air flow passageway and having itslarger diameter end located in the upstream end of the air flowpassageway formed by said tubular wall section, said spring memberdisposed concentrically about said shaft, the smaller diameterdownstream end of said spring member secured in a stationary position tosaid support bar within the downstream continuation of the air flowpassageway, said spring member is free to contract and expand in theaxial direction of the air flow passageway, a pressure plate attached tothe upstream end of said spring member and extending transversely of thedirection of air flow within the passageway and having a centrallydisposed opening through which said shaft member extends so that saidpressure plate is displaceable with said spring member in slidingrelationship with said shaft member, said pressure plate having adiametrical dimension approximately equal to the inside diameter of thedownstream section of the air flow passageway, said pressure plate andsaid wall means combined to form a variable air flow opening at theinlet to the downstream section of the air flow passageway and saidspring member is calibrated to contract and expand in response to theair pressure acting on said pressure plate so that the axially extendingcross sectional area of the variable air flow opening is adjusted on aparabolic curve for regulating the volume of air passing through thedevice.

2. A constant air volume device, as set forth in claim 1, wherein saidtubular wall section has a first diameter, said wall means comprise anannular shaped frame means secured to the inner surface of said tubularmember downstream from the inlet thereto and extending radially inwardlytherefrom and then axially in the downstream direction of the air flowpassageway forming the downstream continuation of the flow passagewayand the downstream continuation has a second diameter which is smallerthan the first diameter of said tubular member, and inner casingextending in the axial direction of said tubular member and secured atits downstream end to said frame means within the downstreamcontinuation of the air flow passageway and extending therefrom in theupstream direction through said tubular member and terminating at aposition spaced downstream from the inlet to said tubular member, saidsupport bar secured to and extending transversely across said frameadjacent and downstream from the downstream end of said inner casing,said shaft member is centrally disposed within said inner casing, theupstream end of said shaft is located upstream from the upstream end ofsaid inner casing, and an outer casing concentrically mounted on theupstream end of said shaft and ositioned in closely spaced relationshipextenorally about sar inner casing, said conically shaped spring memberdisposed concentrically about said shaft is located within said innercasing, said pressure plate which is slidably mounted about said shaftis secured to the larger diameter upstream end of said spring memberextending transversely of and located within said inner casing, saidouter casing having a transverse surface extending across said tubularmember upstream from the upstream end of said inner casing and havingopenings therethrough for admitting air flow to the upstream surface ofsaid pressure plate within said inner casing, said inner casing has atleast one axially extending slit formed in its circumferentialperiphery, said outer casing has at least one axially extending slitformed in its circumferential periphery and arranged for registeringwith the slit in said innner casing, said shaft is rotatably mounted insaid support bar for rotating said outer casing relative to said innercasing for varying the registration of said slits in said inner andouter casing and establishing the extent of the angular opening of theslits, and said spring member and pressure plate are axiallydisplaceable along said shaft within said inner casing for varying theaxial length of the openings of the slits, and means for rotatablypositioning said shaft.

1. A constant air volume device for use in air-conditioning apparatusand the like comprising a tubular wall section forming the upstreamportion of an axially extending air flow passageway having an inlet atone end thereof, wall means secured to said tubular wall section spacedaxially from the inlet end thereof and forming a downstream continuationof the air flow passageway having a smaller cross-sectional area thanand in alignment with the portion of said air flow passageway formed bysaid tubular section, a support bar attached to and extendingtransversely across said wall means forming the downstream continuationof the air flow passageway at a location spaced axially downstream fromthe upstream and of said wall means, a shaft member extending axiallythrough the air flow passageway from said tubular wall section into saidwall means and secured at its downstream and to said support bar, aconically shaped spring member disposed within and extending in thedirection of air flow within the air flow passageway and having itslarger diameter end located in the upstream end of the air flowpassageway formed by said tubular wall section, said spring memberdisposed concentrically about said shaft, the smaller diameterdownstream end of said spring member secured in a stationary position tosaid support bar within the downstream continuation of the air flowpassageway, said spring member is free to contract and expand in theaxial direction of the air flow passageway, a pressure plate attached tothe upstream end of said spring member and extending transversely of thedirection of air flow within the passageway and having a centrallydisposed opening through which said shaft member extends so that saidpressure plate is displaceable with said spring member in slidingrelationship with said shaft member, said pressure plate having adiametrical dimension approximately equal to the inside diameter of thedownstream section of the air flow passageway, said pressure plate andsaid wall means combined to form a variable air flow opening at theinlet to the downstream section of the air flow passageway and saidspring member is calibrated to contract and expand in response to theair pressure acting on said pressure plate so that the axially extendingcross sectional area of the variable air flow opening is adjusted on aparabolic curve for regulating the volume of air passing through thedevice.
 2. A constant air volume device, as set forth in claim 1,wherein said tubular wall section has a first diameter, said wall meanscomprise an annular shaped frame means secured to the inner surface ofsaid tubular member downstream from the inlet thereto and extendingradially inwardly therefrom and then axially in the downstream directionof the air flow passageway forming the downstream continuation of theflow passageway and the downstream continuation has a second diameterwhich is smaller than the first diameter of said tubular member, andinner casing extending in the axial direction of said tubular member andSecured at its downstream end to said frame means within the downstreamcontinuation of the air flow passageway and extending therefrom in theupstream direction through said tubular member and terminating at aposition spaced downstream from the inlet to said tubular member, saidsupport bar secured to and extending transversely across said frameadjacent and downstream from the downstream end of said inner casing,said shaft member is centrally disposed within said inner casing, theupstream end of said shaft is located upstream from the upstream end ofsaid inner casing, and an outer casing concentrically mounted on theupstream end of said shaft and positioned in closely spaced relationshipexteriorally about said inner casing, said conically shaped springmember disposed concentrically about said shaft is located within saidinner casing, said pressure plate which is slidably mounted about saidshaft is secured to the larger diameter upstream end of said springmember extending transversely of and located within said inner casing,said outer casing having a transverse surface extending across saidtubular member upstream from the upstream end of said inner casing andhaving openings therethrough for admitting air flow to the upstreamsurface of said pressure plate within said inner casing, said innercasing has at least one axially extending slit formed in itscircumferential periphery, said outer casing has at least one axiallyextending slit formed in its circumferential periphery and arranged forregistering with the slit in said innner casing, said shaft is rotatablymounted in said support bar for rotating said outer casing relative tosaid inner casing for varying the registration of said slits in saidinner and outer casing and establishing the extent of the angularopening of the slits, and said spring member and pressure plate areaxially displaceable along said shaft within said inner casing forvarying the axial length of the openings of the slits, and means forrotatably positioning said shaft.